[PATCH] drm/i915: do not return invalid pointers as a *dentry

[Greg Kroah-Hartman]

When calling debugfs functions, they can now return error values if
something went wrong.  If that happens, return a NULL as a *dentry to
the relay core instead of passing it an illegal pointer.

The relay core should be able to handle an illegal pointer, but add this
check to be safe.

Cc: Jani Nikula <jani.nikula at linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen at linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: David Airlie <airlied at linux.ie>
Cc: Daniel Vetter <daniel at ffwll.ch>
Cc: intel-gfx at lists.freedesktop.org
Cc: dri-devel at lists.freedesktop.org
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
---
 drivers/gpu/drm/i915/intel_guc_log.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_guc_log.c b/drivers/gpu/drm/i915/intel_guc_log.c
index d3ebdbc0182e..8bf03497dcd8 100644
--- a/drivers/gpu/drm/i915/intel_guc_log.c
+++ b/drivers/gpu/drm/i915/intel_guc_log.c
@@ -140,6 +140,9 @@ static struct dentry *create_buf_file_callback(const char *filename,
 
 	buf_file = debugfs_create_file(filename, mode,
 				       parent, buf, &relay_file_operations);
+	if (IS_ERR(buf_file))
+		return NULL;
+
 	return buf_file;
 }
 
-- 
2.20.1